Passive House – Ultra Efficiency

Green HomeThis column often explores the exciting transformation taking place in the building industry. Green building programs have grown and multiplied at an amazing rate in recent years. We’ve looked at Energy Star, LEED and even the Living Building Challenge. These programs are important because they raise the bar and provide real-world examples of what is possible, not just what is permissible. They drive innovation and change.

Each program has its own unique approach but they all share a common goal of creating a better world by improving the built environment. Energy efficiency is a key to every meaningful green building program but one program in particular takes it to an entirely new level of performance. I’m talking about Passive House, where energy use reductions of 90% are not uncommon. The term applies to many types of buildings, not just homes.

The Passive House concept is a relatively simple blend of ancient wisdom and modern technology. For thousands of years, people have used solar orientation and thermal mass to help keep warmer in winter and cooler in summer. When combined with modern technology that includes super-insulated air-tight building envelopes and ultra-efficient fresh air ventilation systems, the results are impressive to say the least.

Passive Houses are so efficient that the energy they do require can be easily supplied using relatively small photovoltaic and thermal solar arrays for electricity and hot water, respectively. Thus, the goal of carbon-neutral, zero-energy buildings is achieved at minimal cost.

Just how much does a house like this cost? Obviously there is no set answer since most projects of this type are custom and costs vary significantly, but so far the results are promising. Many Passive House projects claim minimal construction cost premiums compared to standard construction practices. Considering that the building’s operating costs are drastically reduced by the energy savings, it’s clear why more people are building to Passive House standards.

It takes a very good contractor to build a Passive House. Attention to detail and proper product selection is essential. For example, triple-pane, ultra-high quality windows push the envelope of thermal performance. The building envelope must avoid thermal bridging and incorporate very high levels of insulation, even under the slab.

Specialized energy-recovery ventilation (ERV) systems replace the typical forced-air heating and cooling equipment found in most homes. The ERV brings in just the right amount of fresh air, pre-conditioned by the outgoing stale air via a high-efficiency heat exchanger. At that point, small amounts of additional heat or cooling is added as necessary. The result is a draft-free, quiet and comfortable living space filled with plenty of healthy, fresh air.

The Passive House certification program started in Germany. There have been tens of thousands built in Europe and it’s no wonder since their energy costs are higher. My last column discussed higher energy prices. Passive House construction is a perfect example of how we can live better with less energy, save money and avoid the distress of rising energy costs.

It’s good to know that people are developing solutions to our most pressing issues, yet we must push strongly for rapid change. We’ve already lost the battle to avoid climate change. We’re only beginning to feel the effects and they will intensify over time. Mitigation is still important, but so is adaptation. Deep green building programs like Passive House provide a solution that addresses both. We can reduce our carbon footprint while creating structures that are much better suited to the challenges of a changing world.

There’s much more to the story, including how we can apply Passive House concepts to our huge inventory of existing homes and buildings. I invite you to explore these ideas and prepare for the inevitable change we must all face. It might turn out to be the best investment you’ll ever make.

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  1. I’ll admit, I hadn’t heard of passive houses, but it’s a very interesting concept, that doesn’t seem all that hard to grasp. I’m glad to see that it is taking hold here in the U.S., and that it is amenable to existing homes as well. Now folks just need to get on board. It helps with columns like yours that explain it in an easy to understand way. Thank you for teaching me my “something new” for today!